643783 has 4 divisors (see below), whose sum is σ = 735760. Its totient is φ = 551808.

The previous prime is 643781. The next prime is 643847. The reversal of 643783 is 387346.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 643783 - 2¹ = 643781 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45978 + ... + 45991.

It is an arithmetic number, because the mean of its divisors is an integer number (183940).

2⁶⁴³⁷⁸³ is an apocalyptic number.

643783 is a deficient number, since it is larger than the sum of its proper divisors (91977).

643783 is an equidigital number, since it uses as much as digits as its factorization.

643783 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91976.

The product of its digits is 12096, while the sum is 31.

The square root of 643783 is about 802.3608913700. The cubic root of 643783 is about 86.3468505277.

The spelling of 643783 in words is "six hundred forty-three thousand, seven hundred eighty-three".